1. Technical Field of the Invention
The present invention relates to billing ID correlation, and more particularly, to a system and method for correlating billing ID information for subscribers roaming between wireless communication systems utilizing differing technologies.
2. Description of Related Art
Within cellular networks, a mobile subscriber may roam between service areas of different networks. Various techniques have been developed to enable a mobile subscriber to continue being provided with mobile telephone services once they have left their home service area. In a first alternative, once a mobile subscriber travels into a new mobile switching center (MSC) coverage area and turns on their mobile station for the first time, the mobile station attempts to register with the servicing MSC for the area by transmitting an associated identification number known as the international mobile subscriber identity (IMSI) number or mobile identification number (MIN). The serving MSC communicates with the home location register associated with the mobile station using the received IMSI/MIN. This communication is to inform the HLR of the mobile station""s new location and to receive requisite subscriber information from the HLR necessary to provide mobile services to the newly registering mobile station.
However, when mobile subscribers move between networks utilizing different technologies, for example, a GSM system utilizing a GSM MAP protocol and a TDMA system using a ANSI-41 protocol, the various information required to be transmitted between the networks creates problems in converting information between the protocols useable by each system.
One of the problems arising with subscribers roaming from a GSM system to a TDMA system involves the inability to track billing information for a GSM subscriber within a TDMA system. This arises because of the differences in the way billing ID information is transmitted within the separate systems. The billing information is necessary in order to correlate a billing record generated in the gateway mobile switching center (GMSC) with a billing record generated in a visited mobile switching center (MSC). Since the billing information formats are different between GSM and TDMA networks (and also GSM networks where TAP is the utilized standard), there exists a need for a system capable of providing billing information when a GSM subscriber roams outside of its home technology network into a system utilizing a differing technology.
The present invention overcomes the foregoing and other problems with a system and method for generating a billing identifier for a call to a subscriber from-a GSM network which is presently located within a TDMA or other technology network. A mobility gateway interconnecting the GSM network with the TDMA network receives a call message from the GSM network which does not include a billing identifier. A functionality within the mobility gateway generates a billing identifier enabling billing records within the TDMA network to be associated with the subscriber from the GSM network.
The billing identifier includes a mobility gateway switch ID, a mobility gateway switch number and an additional part which identifies the mobile country code and a mobile network code for the subscriber. The mobility gateway transmits the billing identifier to the TDMA network. Later, the mobile country code and mobile network code for the subscriber from the GSM system may be determined from the billing identifier, and the billing record within the TDMA network associated with the subscriber using this information.